Abstract: The soil mass in the abandoned soil site has complex gradation and low strength, and landslides and debris flows are highly likely to occur under extreme rainfall conditions. To deeply analyze the influence of rainfall and different fill materials on the stability of the abandoned soil site, the authors conducted a systematic study on the permeability and mechanical properties of the abandoned soil site under different soil-rock ratios through a large number of indoor and outdoor experiments. The experimental results show that as the soil-rock ratio increases, the permeability coefficient of the soil decreases according to a negative exponential function curve. And the failure deviatoric stress first increases and then decreases, reaching its peak when the soil-rock ratio is 6∶ 4. The numerical simulation analysis of seepage and stability of the slope under different rainfall conditions was carried out, based on the soil parameters obtained from the experiments. The results show that the saturation of the slope increases with the increasing of rainfall duration. And the pore pressure would increase, and the matric suction would decrease. So the safety factor of the slope decreases with the decreasing of shear strength. The research proves that the soil-rock ratio has a significant impact on the seepage and stability of the slope. During slope construction, the filling positions of different soil-rock ratio fill materials should be reasonably planned to improve the stability of the abandoned soil site. The research could provide references for the design of the abandoned soil site, the construction of the abandoned soil filling, and the rational utilization of different fill materials.